The present invention relates to a riser for a coke oven of the type employed to remove the fill gases from a cokeoven chamber into a collecting main, and specifically of the type including a raisable cover for closing an opening in the corner area of the riser, such cover being mounted on a shaft on a supporting device of the riser.
Riser covers typically have a diameter approximately equal to the diameter of the riser. Since the risers have a relatively large diameter of, e.g. 70 cm, the covers are of necessity quite heavy. Consequently, considerable forces result when the cover is opened, and such forces must be absorbed by the riser. The corner element of a riser, through which the fill gases rising from the oven chamber are guided into the collecting main and wherein the opening is provided, is ordinarily made in the form of a casting due to its shape. On such cast corner element there is also formed the supporting device for the shaft on which the cover is mounted. Thus, when the cover is opened or closed, the forces of reaction to the acceleration or retardation of movement of the cover must be absorbed by the cast corner element. It has been observed that cracks are formed in the cast corner element due to such forces being transmitted thereto when the cover is rapidly accelerated and retarded. This can be explained as resulting from transmitting sudden and large shocks to the cast corner element.